Artificial horizon



E. G. FISCHER.

ARTIFICIAL HORIZON.

APPLlcATloN ElEEnV 1uNE 5. 1919.

Patented Mar. 21, 1922.

SHEET 1.

2 SHEETS- lll f. W afm 6. n f l E. G. FISCHER.

ARTIFICIAL HORIZON.

APPLICATION FILED JUNE5. 1919.

Patented Mar. 21, 19.22.A

2 SHEETS-SHEET 2.

UNITED STATES ERNST G. FISCHER, OIF WASHINGTON, DISTRICT OE COLUMBIA. Y

ARTIFICIAL HORIZON. l

Speclcation of Letters Patent.

Application fled June 5, 1919. Serial No. 301,920..

To all whom t may concern:

Be it known that I, ERNST G. Fisorrnn, a citizen of the United States, residing at IVashington, in the District of Columbia, have invented a new and Improved Artificial Horizon, of which the following is a specification.

This invention has for its object to provide an artiiicial horizon for sextants,hand or mounted levels, and other surveying and astronomical apparatus requiring exact denition of either the horizon or vertical.

In its generic nature the invention comprises a pendulum -device having a horizon line whichis cooperative with another horizon line that is relatively fixedly mounted on the instrument whereby when the instrument is moved to bring both lines in alignment, the same will correspond to the true horizon.

In its more specific nature the invention includes a pendulum-vane of small mass but large area, suspended upon knife edges, in its motions opposed to air or a suitable lliquid so that its oscillations are damped 'and as nearly Adead-beat as is practicable yet sensitive to the smallest departures from the normal; a small light arm being attached to the pendulum vane' and carrying a piece of fine platinum Wiremounted horizontally, there being'a similar piece of platinum wire fixed to the apparatus supporting the pendulum-vane in sucjh manner that, when adjusted and the vane is atfrest, the Wires are 1n one horizontal line. Y

Inasmuch as my invention has been especially designed for use in connection with the sextant, I have illustrated the invention as applied to such an instrument and shall describe the same in that relation, 'although I wish it understood that in its use'the invention is notlimited to sextants but -may be employed Wherever a device of this nature is found useful.

In its more subordinate nature, the invention also includes those novel details of construction. combination and arrangement of parts, all of which will be first vIully described and then be specifically pointed out in the appended claims, and illustrated in the accompanying drawings, in Which-:-

Figure 1 is an elevation of'a sextant with the invention applied.V i v Figure 2 is an enlarged vertical longitudinal section of the invention. f Figure Vr3 is areduced transverse section on the line 3 3 of F igure` 2, looking in the direction of the arrow.

Figure 4 is an enlarged elevation of the cap disk which supports the operative parts of the pendulum mechanism.` i

Patented Mal-.21, 1922. V

Figure 5 is a ydetail perspective view of the pendulum mechanism and the bracket which supports the same. f Figure 6 isan enlarged detail .view of a port-ion of the same.v Y Y In the-drawings, in which like numerals of reference indicate like parts in all of the iigures, lfrepresents thesextant whichis .of the ordinary construction and, per se, forms no, part of the invention and a detailed de- ,scriptionl of the same is thought to be unnecessary. lVhen my invention is applied to sextants, the same isprovided with an 'arm 2 to which a bracket 3 is secured that is provided With. a U-shaped portion formed by bending back a part 4 `on which part et the device is mounted. .5. is an adjustmentk screw by which the axis of the'device may be inclined to line up properly with the'telescope of the sextant.. Secured to the platea isla kholder@ in which is suitably. mounted atube r. The forwardy end of the tube 7 is provided with a collimating. lens whichV is so mounted that its principalioous; lies inthe horizontal Wires 40%@ hereinafter again is mounted the'pendulum device 34. which constitutes the essential part of the' device. This device consists of a receptacle 15 mounted von theend oi' the tube 7 and bored `referred to. Ati the outer end of the tube 7v Y i holder 15 on which the pendulum'aparatus is mounted, the cap 19 being secure by cap screws 20, as shovvn.=Y f

The tube 7 isv provided with a window` 9 that is mounted `in. the inwardly projectingV collarv 10 so constructed `astoprevent the accumulation of air bubble'sfon Athe glass of the Window 9' when liquid is used as a dampin medium. Adjacent to thefwindow tithe tue 7 is provided-with a transparent partition 4 5, Whenliquid isused as a damping medi-um, aswill be later explained;

12 isa lamp-socket mountedfona cli holder 11 that clips over the tube holder 6 and can be turned about theaxis-vof'thetube (see Figure 3) Sothatythebulb 13' will-be brought with its transparent portion \14 to register with the Window 9 or be moved to one side out of register with the same (see dotted lines Figure 3) it being understood that the bulb 13 is preferably rendered o aque, except for the area 14 directly above t e window`9 when the parts are in the position shown in Figures land 2. The illuminating power for the lamp 13 can be obtained from any desired source, either by a battery in the handle of the sextant, (not shown) or inany other desired Way.

By referring now directly to Figures 2, 4, 5 and 6, the construction and manner of mounting the pendulum-vane will be clear. 23 designates a bracket body having knife bearing lugs 25 projecting from the same, the lugs 25 having V ooves 26 to receive the knife ends 27 which are connected. by lthe cross bar 28. The knife bearing ends 27 are bevelled off, as at 29, (see Figure 6) so that only a point will be `presented to the endplates 3() at the pivotal axis `of the in horizontal ali nment with the saine.

pendulum to prevent lateral displacement of the bearing knives 27 in their grooves 26 (see Figure 6). 3() designates end plates having ears 31 apertured and `secured by screws `32 to the bracket 23, the plates 30 lying against the bearing projections 25 at the ends ofthe knife bar, as shown andv they are preferably of greater Vdepth than the depth of the bearing projections 25 so as to form stops at46 to prevent theknives 27 falling out of the rooves 26 when the instrument isinverte or jarred. The bracket body 23 is secured at 24 to the cap 19.

`The knife bar 28 is provided With a plurality ofrecesses133 in which the arms 35 of the pendulum vane 34 are held by bending the same around the'bar `28, a third `notch being provided Ato receive the end 330i the `arm 37 which is rigidly secured to tlie bar `28 and' projects into the tube 7, the arm v37 being provided at'its forward end with a socket `39 to hold a fine `Wire 40, preferably `ofplatinum, thewire 40 lying parallel to the pivotal axis of the pendulum-vane'and 41 isa fixed arm t at is secured at 42 to the bracket 23 and it also has a socket 43 to `hold a Wire 44, also preferably of platinum, the wires 40 and 44, Whefnthe apparatusis adjusted' andthe pendulum-vaneisat rest,

lyinginalignment withy one `another so as toconstitute-the artificial horizon line (see res 2, 4land 5). .f

n Suse, the light from the lamp 13 is `directed-1through` thewindow 9 onto the wires 40 and 44 `and transmitted as parallel Wraysby the lens8 to lthe telescope ofthe sextant. .1 In' day* light observations the necessary light `may beadrni-tted through the "Window ufrom above, andfin that event'the lampf-13fisgmovedto ithe dotted position :shown in Figure-asoma to expose the wiriand the sides of the containing chamber,and

the space between the faces of the vane and the Walls of the chamber against which it swings may be also varied to vary the amount of damping.

From the foregoing, it Will be observed that when the sextant and 'artificial horizon are properly adjusted and the instrument is held so that the iixedvvire 44 and the pendulum wire 40 appear as one line, While the image of the celestialorterrestrial object is either in contact with orrbisected by this line,the reading of the Vernier on the arc will be theV altitude of the body observed.

From the foregoing description, taken' in connection with the accompanying drawings, it is thought the complete construction, operation, uses and advantages of-my invention Will be readily understood by those skilled in the art.

WVhat I claim is :M I 1. A device of the character described comprising a support, a pendulum-vane `mounted on said support, ay line carried by said vane, line relatively fixed -with regard to said support and cooperativevvith the pendulum vane, and a second indicator relatively fixed and cooperatingvvith-the irstlmentioned indicator. j

3. ,ln a device of the cliaracterdescribed,

fthe knife and an indicator operative With a housing having a chainberclosedubya cap, f

a bracket mounted on the vcap and 'having knife receiving bearings, a knife fmounted in said-bearings, a pendulum vanemounted on the knife and an indicator operative with the pendulum vane,a second indicator relal tivelyv fixed and cooperating with the first mentioned indicator, and means for retain-` ing the knife in its bearingsfa'gainst, dis- Placement.` f

4. In a device of the characterV described,

`a housing having achamber closed by a cap,

a bracket mounted on the cap and having knife receiving bearings, a knife mounted in said bearings, a pendulum vane mounted on the knife and an indicator operative With the pendulum vane, a second indicator relatively fixed and cooperating with the first mentioned indicator, and means for damping the oscillations ofthe pendulum vane.

In a device of the character described, a housing having a chamber closed by a cap, a bracket mounted on the cap and having knife receiving bearings, a knife mounted in said bearings, a pendulum vane mounted on the knife and an indicator operative with the pendulum vane, a second indicator relatively iixed and cooperating With the first mentioned indica-tor, means for retaining the knife in its bearings against displacement, and means for damping the oscillations of the pendulum vane.

6. In apparatus of the class described, a tube, a chambered body mounted on the tube and having a chamber in communication therewith, a support mounted Within the chamber and having bearings, Ya pendulum-vane mounted on said bearings, an arm carried by the vane and projecting into said tube, an indicator carried by the arm, a second indicator relatively fixedly held in the tube and adapted to align with said pendulum indicator when the tube is in the hori zontal position, substantially as shown and described.

7. In apparatus of the class described, a tube, a chambered body mounted on the tube and having a chamber in communication therewith, a support mounted Within the chamber and having bearings, a pendulumvane mounted on said bearings, an a'rm carried by the vane and projecting into said tube, an indicator carried by the arm, a second indicator relatively fixedly held in .the tube and adapted to align with said pendulum-vane indicator when the tube is in t-he horizontal position, said tube having a ivindoiv through which light may be ad- Amitted directly/onto said indicators.V

8. In apparatus of the class described, a tube, a chambered body mounted on the tube and having a chamber in communication therewith, a support mounted Within the chamber and having bearings, a pendulumvane mounted on said bearings, an arm carried by the vane and projecting into said tube, an indicator carried bythe arm, a.

second indicator relatively fixedlyheld in the tube and adapted to align With said pendulum-vane indicator when the tube is in the horizontal position, said tube having a window through which light may be admitted onto said indicators, and an arti,v

ficial illuminating medium mounted on said tube and adapted to project its light through said Window, said artificial illuminating pendulum-vane comprising a thin body of relatively large area opposed to the direction of movement, said body being of small ,mass substantially as shown and described.

l0. In a device of the character described, a containing support, a pendulumvane mounted in said support, a fixed indicator line Within the support, a second indicator line carried by the pendulum-vane to cooperate iviththe fixed indicator line, said pendulum-vane comprising a'thin body of relatively large area opposed to the direc tion of movement, said body being of small mass, said containing support including a chamber for the pendulum-vane which closely conforms to the edge of the vane and a fluid damping medium contained Within said support, substantially as shown and ide-I scribed.

1l. In a device of the character stated, a containing support, a pendulum-vane mounted in` said support, a fixed indicator line Within the support, a'second indicator line carried by the pendulum-vane and adapted to cooperate with the fixed indicator line and lie in longitudinal alignment with thesame When the instrument is in the horizontal position, said pendulum-vane comprising a sheet metal body having a relatively large area opposed to the direction of movement, said body being of small mass substantially as shown and for the purposes described.

l2. A device of the character described comprising a support, a pendulum-vane on said support, a line carried by said pendulum-vane, a relatively fixed line carried by saidl support, said lines adapted to lie in longitudinal alignment with their axes coinciding when the device is in the horizontal position, substantially as shown and described.

13. In a device of the character described, a containing support, a Apendulum-vane mounted in said support, a relatively fixed indicator line mounted in the support and a second indicator line carried by the pendulum-vane, a collimating lens carried by the support, said lines being positioned to lie in axial alignment passing through the principal focus of said lens When the instrument is in the horizontal position, and means by which said lines may be illuminated to cause their. image to be transmitted through the collimating lens.. f

ERNST G. FISCHER. 

